As for a resistive element formed on a semiconductor layer, a resistive impurity layer is exemplified. The resistive impurity layer is formed, for example, by doping an impurity to the semiconductor layer made from silicon substrate. The resistive impurity layer is formed, for example, in a region (active region), electrically isolated by an element isolation region. In this case, for a normal operation of the resistive impurity layer, it is important to ensure insulation between the resistive impurity layer and its peripheral region sufficiently by using the element isolation region.